The present invention relates to a numerical analysis system using a computer, and more particularly to an apparatus for forming an analytical shell model from a solid model of a thin plate structure formed by a three-dimensional configuration modeler.
An example of forming an analytical shell model from a solid model of a thin plate structure is described in JP-A-6-259505 and JP-A-2002-207777. According to an analytical model forming method described in JP-A-6-259505, even for configuration data expressed by boundary representation not having configuration features, in order to simplify a configuration with easy manipulations, a configuration model is converted into an internal data structure and geometrical features such as parallel and connection state are extracted from the configuration data. A configuration element of a portion of a simplified configuration and the type of simplification are input, a target configuration to be simplified is extracted from the geometrical features, and it is instructed to execute a configuration process to combine deletion necessary for simplification. Thereafter, the geometrical configuration of a target configuration element and a configuration element to be connected to the target configuration element is altered to delete a meaningless phase element.
According to an analytical model forming method described in JP-A-2002-207777, in order to efficiently form a neutral surface mesh model to be used for analysis in accordance with configuration data generated by a CAD system, a two-layer structure void mesh model is formed by utilizing surface information in CAD data. Each contact point of the model is moved in accordance with a motion vector set based on the configuration to gather model contact points on the neutral surface and generate the neutral surface model.
However, the analytical model forming method described in both JP-6-259505 and JP-A-2002-207777 does not consider that a medial surface model suitable for analysis is determined uniquely from a configuration model. Namely, when a configuration model having thickness is converted into a medial surface model which is a pseudo model, although it is effective that the configuration of the medial surface model is changed in accordance with the type of analysis for the configuration model such as structural analysis and collision analysis and with analysis boundary conditions, only one configuration model can be formed. Therefore, there arises the problem that it is difficult to form a medial surface model suitable for analysis.